| Date | Tue, 27 Sep 2022 13:34:07 +0200 | From | Peter Zijlstra <> | Subject | Re: [RFC PATCH 12/23] thermal: intel: hfi: Convert table_lock to use flags-handling variants |
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On Fri, Sep 09, 2022 at 04:11:54PM -0700, Ricardo Neri wrote:
> --- a/drivers/thermal/intel/intel_hfi.c > +++ b/drivers/thermal/intel/intel_hfi.c > @@ -175,9 +175,10 @@ static struct workqueue_struct *hfi_updates_wq; > static void get_hfi_caps(struct hfi_instance *hfi_instance, > struct thermal_genl_cpu_caps *cpu_caps) > { > + unsigned long flags; > int cpu, i = 0; > > - raw_spin_lock_irq(&hfi_instance->table_lock); > + raw_spin_lock_irqsave(&hfi_instance->table_lock, flags); > for_each_cpu(cpu, hfi_instance->cpus) { > struct hfi_cpu_data *caps; > s16 index;
^^^^ Anti-pattern alert!
Now your IRQ latency depends on nr_cpus -- which is a fair fail. The existing code is already pretty crap in that it has the preemption latency depend on nr_cpus.
While I'm here looking at the HFI stuff, did they fix that HFI interrupt broadcast mess already? Sending an interrupt to *all* CPUs is quite insane.
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